Fluid flow meters have been employed in a wide variety of environments and applications. In addition, a plethora of technologies have been implemented in creating appropriate flow meters for every possible fluid measurement including differential pressure flow meters including, for example, flow nozzles, orifice plates, venturi tubes and variable area rotameters. Flow nozzles are most often used in industrial applications to measure air and gas flows and are available in a number of sizes and materials. There are calorimetric flow meters which are based upon two temperature sensors that are in close contact with a fluid. There are coriolis flow meters that use the coriolis effect to measure the amount of mass that moves through an element and ultrasonic Doppler flow meters that determine if a fluid moves towards a transducer or away from it to measure the frequency differences. Turbine flow meters are strategically placed in a conduit and the fluid passing over the turbine and thus moving the turbine in angular rotation does so in response to fluid flow.
With virtually all of these technologies, it can only be as accurate as the particular flow characteristics of an incoming fluid stream. Turbulence, in its numerous forms, causes these meters to have inaccurate readings. Knowing that turbulence is induced by upstream disturbances caused by such things as pipe elbows, valves, restrictions, diameter reductions and the like suffer inaccuracy as a consequence.
Inaccuracies in fluid flow imposed by the physical environment surrounding the fluid can be adjusted by the use of a meter factor which is used to correct the unique installation creating the inaccuracy. It has been suggested that a flow straightener plate or tube bundle which segregates the internal fluid flow within a conduit to approach the meter in parallel streams would be beneficial. This method imparts a backpressure to the fluid flow which reduces its velocity profile and eliminates swirl. However, this does not totally eliminate the velocity profile. In addition, this technique requires fifteen pipe diameters of straight pipe run upstream of the correction plate and a minimum of eight diameters of straight pipe run downstream prior to the meter.
It has also been suggested to use a baffled flow straightener which temporarily increases the turbulence of the fluid and then releases the result to a pipe upstream of the meter. It has been found that this method is inconsistent at best and does not adequately prepare the flow for a uniform approach to the meter. In addition, this technique requires ten pipe diameters of straight pipe run upstream of the plate and a minimum of five diameters of straight pipe run downstream prior to the meter.
The requirement for accurate flow measurements is becoming more and more acute. For example, flow meters are employed to measure the volume of petroleum crude discharged from a tanker or alternative storage vessel. As crude prices exceeds $70 a barrel, flow meters which even have the slightest degree of inaccuracy can result in mismeasurements costing many dollars in losses.
It is thus the object of the present invention to provide a flow conditioner which can be employed upstream of a fluid flow meter to eliminate substantially the fluid's velocity profile and to segregate the flow into parallel streams, thus optimizing repeatability and minimizing the meter factor.
A further object of the present invention is to provide a flow conditioner upstream of a fluid meter requiring no pipe diameters upstream of the device to provide repeatable and accurate meter readings.
These and other objects will become more readily apparent when considering the following disclosure and dependent claims.